JSL014-1_Jabiru_Cylinder_Head_Inspection_4.pdf

Jabiru Service Letter: Cylinder Head Inspection

JABIRU AIRCRAFT PTY LTD P.O. Box 5186 Phone:+61 7 4155 1778 Bundaberg West Fax:+61 7 4155 2669 Queensland, Web: www.jabiru.net.au Australia. Email: [email protected]

JSL 014-1 Release Date: 1st December,

2014

Effective Date: 13th December,

2014

Affected Models: See Applicability

S/No. Range: See Applicability

of 14

SERVICE LETTER: JSL 014-1

Issue: 1

Date: 7th December 2014

Subject: Jabiru Cylinder Head Inspection

Release Date: 1st December, 2014

Effective Date: 13th December, 2014

Affected Models: All Jabiru Engines

1 Table of Contents

1 TABLE OF CONTENTS ...................................................................................................................................... 1

2 GENERAL ............................................................................................................................................................ 2

2.1 RECURRENCE ................................................................................................................................................ 2

3 APPLICABILITY .................................................................................................................................................. 2

3.1 APPLICABILITY PROCESS ................................................................................................................................ 2 3.1.1 Example 1: .............................................................................................................................................................. 4 3.1.2 Example 2: .............................................................................................................................................................. 5 3.1.3 Example 3: .............................................................................................................................................................. 5

4 TIME OF COMPLIANCE ..................................................................................................................................... 6

5 RECOMMENDED ACTION ................................................................................................................................. 6

5.1 CYLINDER HEAD REMOVAL AND INSPECTION. .................................................................................................. 6 5.2 FOLLOW-ON INSPECTIONS ............................................................................................................................. 9

6 JABIRU ENGINE MANUALS ............................................................................................................................ 10

7 GENERAL ENGINE MAINTENANCE NOTES.................................................................................................. 10

8 REMINDER OF CURRENT PRACTICES ......................................................................................................... 10

8.1 NOTES OF OPERATION ................................................................................................................................. 11

9 CHECKLIST. ...................................................................................................................................................... 12

10 CONTINUED OPERATING SAFETY REPORTING FORM .............................................................................. 13




2014

Effective Date: 1st December,

2014



of 13

2 General

This service letter has been prepared to assist operators in identifying and addressing a range of potential issues affecting the operation of Jabiru engines.

NOTE

Incomplete review of all the information in this document can cause errors. Read the entire Service Letter to make sure you have a complete understanding of the requirements.

2.1 Recurrence

The inspections detailed herein are carried out ONCE except as detailed below.

Where an engine is assessed as Group 3 or Group 4 it is recommended that, after the initial inspection in accordance with Table 1, a cylinder head is removed at each 100-hourly or annual inspection (whichever is the sooner) and inspected as detailed in Section 5.1. The applicability procedure detailed below should be repeated at each inspection to monitor for changes to risk grouping.

3 Applicability

As noted above, this letter addresses several different potential issues. A range of contributing factors have been identified and the process below is used to determine how much risk applies to a given engine and, from that, what level of work is recommended.

The risk factors for the engine are primarily environmental or operational and so this approach has been used instead of conventional serial number range applicability format.

This is a self-administered risk assessment, designed to minimize imposition on low-risk engines while recommending appropriate inspections on high risk engines.

Honesty and subjectivity is critical to achieving the desired result. Examples are provided and Jabiru Aircraft may be consulted if there are questions on any points: if in doubt, use the more conservative value.

3.1 Applicability Process

i. Refer to Table 2: Read each and select the answer most applicable to the engine. ii. Write the “Response Value” for each answer in the “Results” column of the table. iii. Add all of the entries in the results column and write the total in the box provided. iv. Reading from Table 3, determine which group the engine falls into. v. Carry out inspections / follow-on inspections as detailed.

Table 1 – Inspection Requirements by Group.

Group Inspections

Group 1 None.

Group 2 Visual inspection of engine, follow-up on points detailed in Section 5.2.

Group 3 Inspect 1 critical cylinder heads of engine as detailed in Section 5.1. Follow-up on points detailed in Section 5.2.

Group 4 Inspect ALL cylinder heads of engine as detailed in Section 5.1. Follow-up on points detailed in Section 5.2.




2014


2014



of 14

Table 2 – Applicability Assessment

Criteria Response Value

Result 0 1 2 3 4

CHT: Does the engine experience CHT indications above the start of the yellow line (180°C or 350°F) during operation.

Never Sometimes

close In exceptional

conditions. Regularly All the time.

Oil Temp: Does the engine experience Oil Temp indications above the start of the yellow line (100°C or 212°F).

Never Sometimes


conditions. Regularly All the time.

EGT: Does the engine experience EGT indications above 720°C or (1328°F) during operation.

Never Sometimes


conditions. Regularly / No EGT Gauge

All the time.

Flight Training: Is the engine used for flight training (or hired out for any other purpose).

Never 25% or less of

the time. 25-50% of the

time. 50 - 75% of

the time. 75 - 100% of the time.

Time Since Overhaul: How many hours since the engine had a “top end overhaul” or equivalent maintenance (including replacement of all valves)

0 – 200 hours

200 – 400 hours

400 – 600 hours

600 – 800 hours

800 – 1000 hours.

Fuels: Is the engine operated strictly in accordance with Jabiru operating recommendations for the particular fuels being used – detailed in Service Letter JSL007-5 (or later approved issue)

Always 100 – 75% of

the time. 75 - 50% of

the time. 50 - 25% of

the time. 25% or less of the time.

Dust: Is the engine operated in dusty environments. Never 25% or less of

the time. 25-50% of the

time. 50 - 75% of

the time. 75 - 100% of the time.

Operational History: Have you had upper cylinder issues with Jabiru engines in the past 2 years.

Never 1 or 2 minor

issues. Several minor

issues

1 or 2 significant

issues.

Several significant

issues

TOTAL

Table 3 – Applicability Group

Group 1 Group 2 Group 3 Group 4

TOTAL 0 - 4 5 - 8 9 - 12 13 - 16 17 - 20 21 - 22 23 - 28 28 - 32




2014


2014



of 14

3.1.1 Example 1:

An engine is operated in a flying school based in rural Queensland. The owner flies his aircraft about once a month, the rest of the time it is in the hands of the CFI, his instructors and the local maintenance organisation. In summer the instructors note that engine temperatures are frequently high. No EGT gauge is fitted. The engine had a top-end overhaul 809 hours ago and almost never operates from gravel runways. MOGAS from the above-ground airstrip tank (which holds several thousand litres and is refilled every few months) is used. The fuel is supplied by the owner of the airstrip; documentation is not provided. The engine has had chronic low compression problems with cylinder #3 since 400 hours TIS. The seat has been re-cut twice and the exhaust valve replaced 150 hours ago. Another Jabiru engine in the same flying school suffered an exhaust valve failure 18 months ago. Response Values: CHT: 3, OIL T: 3, EGT: 3, Flight Training: 4, TSO: 4, Fuel: 4, Dust: 1, Operational History: 3. TOTAL 25. Applicability Group 4, actions per Table 1. Notes:

- Temperatures: These answers are subjective as the person completing the assessment is not always in the aircraft to monitor temperatures. Be conservative!

- Fuel: Jabiru’s fuel guidance as detailed in JSL007 notes that, when operating an aircraft

on MOGAS “…Drums, jerry cans and above-ground tanks are not considered approved tanks…” And “…Do not use MOGAS which has been stored for more than 1 month outside of an approved gasoline storage tank…”. In this case the tank is not an approved type, is supplied without documentation and is stored improperly. JSL007 also notes that “Due to QA considerations, operators who use MOGAS do so at their own risk.” In this case, fuel is a high risk point for the engine.

- Operational History: The issues affecting this engine directly would score a 2.

However, an engine operated and maintained by the same organisations has had a severe issue within 2 years. How an engine is operated and maintained is a critical factor in its reliability and it is reasonable to expect that the engine in question was operated and maintained in the same way as the engine which failed – therefore the higher value was used.




2014


2014



of 13

3.1.2 Example 2:

An engine operated in an owner-run flying school based in rural South Australia. During summer the owner/instructor flies morning and afternoon to avoid peak temperatures, teaches his students to manage engine temperatures but sometimes notices engine temperatures in the yellow range. No EGT gauge is fitted. The engine had a top-end overhaul 633 hours ago and often operates from gravel runways. AVGAS is used wherever possible but a few times a month MOGAS from drums has to be used. The operator monitors pull-through and leak down results closely and 100 hours ago re-cut a valve seat to restore compression on cylinder #2. Response Values: CHT: 2, OIL T: 2, EGT: 3, Flight Training: 4, TSO: 3, Fuel: 2, Dust: 4, Operational History: 1. TOTAL 21. Applicability Group 3, actions per Table 1. Notes:

- In this case cylinder #2 has required attention and as the valve was re-cut and re-used (not replaced) would be a natural choice for checking. Cyl #4 would typically be the second head checked.

3.1.3 Example 3:

An engine is operated in a private share-syndicate aircraft based in rural Victoria. One or another of the owners fly the aircraft once every few months. The aircraft is maintained by a local maintenance organisation. The aircraft is fitted with a digital engine instrument monitoring temperatures (including EGT) on 2 cylinders only. The owners have never seen out-of-limit temperatures indicated though they know that on really hot days the temperatures are in the upper-green range. The engine has completed 241 hours TIS. The owner keeps the aircraft topped up with MOGAS about half of the time – the remainder he fills it with AVGAS at a neighbouring airport. Compression on Cylinder #4 is slightly lower than the rest of the cylinders but within limits. The aircraft operates mostly from bitumen or well-grassed strips. Response Values: CHT: 2, OIL T: 2, EGT: 3, Flight Training: 0, TSO: 1, Fuel: 4, Dust: 1, Operational History: 1. TOTAL 14. Applicability Group 2, actions per Table 1. Notes:

- Temperatures: These answers are subjective as the person completing the assessment is not always in the aircraft to monitor temperatures and not all cylinders are monitored. In the case of EGT this has resulted in a higher response value.

- Fuel: The type of operations described results in the aircraft sitting for long periods and

then operating with mixtures of MOGAS and AVGAS in its tanks: this is strongly discouraged in JSL007.




2014


2014



of 13

4 Time of Compliance

The effective date of this Service Letter JSL 014-1 is 13th December, 2014.

All requirements prescribed in Section 5 are recommended to be performed at the next scheduled maintenance.

All current maintenance requirements including those revised in section 7 must be practiced at the time intervals prescribed in the relevant Engine manuals.

5 Recommended Action

5.1 Cylinder Head Removal and Inspection.

CAUTION

TO PREVENT BURNS, LET THE ENGINE COOL FOR 1 HOUR OR LONGER AFTER SHUTDOWN BEFORE REMOVAL OF THE HEAD.

Remove the number of cylinder heads specified in Table 1 from the engine and carry out the inspections detailed below. Ideally the head which is inspected should be that which typically operates the hottest. This will be known if an Engine Management System (EMS) is installed, otherwise one of the back cylinders are often hottest. The amount that head bolts turn when checking bolt torque during maintenance is a good indication of operating temperature – the more a bolt turns the hotter the head – so the head with bolts that move the most is the best candidate for these inspections.

i. Follow the instructions for cylinder head disassembly as detailed in the Engine Overhaul Manual (JEM0001) such that the rockers, valves, collets, valve springs and valve spring washers are removed from the head.

ii. Visually inspect the inlet and exhaust valve seat, check the seats do not have excessive carbon build-up and the seats are level in the head (i.e. not protruding or sunken).

iii. Inspect the valve guides. Check there is not excessive carbon build-up. Check the diameter of the guide is within the limits specified in the build tolerances table in JEM0001. Use a ‘Go-No Go’ tool (as pictured below – www.prittie.com.au). Ream out guide if required to meet the tolerances specified in the Engine Overhaul Manual (JEM0001). A high quality adjustable straight reamer should be used (e.g. the Sutton MA8 6.35 – 7.15mm). The procedure of measuring and reaming valve guides requires extensive skill and experience as well as specialized tools. As noted in Section 7, only appropriately trained and approved personnel must carry out these tasks.




2014


2014



of 13

Figure 1: Go-No Go Gauges

iv. Inspect both valves, checking for corrosion and abrasion on the stem. Inspect the bottom of the stem using a 10X magnifying glass. This area will first need to be polished clean (using non-abrasive methods to avoid damaging the valve) so the surface can be inspected. Check the stem for bluing and transverse stress cracks which would indicate overheating. If cracks are found then all valves in the engine must be replaced. (See Figure 2). Report to Jabiru using Continued Operating Safety Form COSM-1 below.

Figure 2: Valve with extensive stress cracks.

v. Check the collet grooves on the valves are clean and free from corrosion and other contaminants, clean as necessary. Similarly check the collets themselves. Reassemble the collets on the valve stem and check the valve can freely rotate. Binding parts are unacceptable. Replace parts if necessary.

vi. Inspect the top and bottom spring washers for wear. Signs of excessive wear also indicate washer rotation caused by binding collets. Replace parts if necessary. Refer to JSL-008 21st Dec 2012.

vii. Visually inspect the valve springs with at least 10X magnification. If any nicks, inclusions or corrosion pitting is seen, all springs in the engine must be replaced. Measure the length of the uncompressed spring, check it is within the limits of the Engine Wear table in JEM0001 and replace parts falling outside these limits.




2014


2014



of 13

viii. Inspect rockers. In particular inspect the condition of the rocker bushes, check the

bush for melting or other deterioration. Insert the rocker shaft and check that the rocker moves freely (but not loosely) on the shaft. Replace rocker bushes with new parts if required. In the photograph below the rocker bush has most of the inner lubricant material melted away. In this case all the rocker bushes from all cylinder heads should be replaced. Report to Jabiru using Continued Operating Safety Form COSM-1 below.

Figure 3: Badly worn rocker bush.

ix. If any issues are detected on the one cylinder head inspection, then all the other cylinder heads must also be removed and the fore mentioned inspections conducted.

x. Re-assemble and install head as per Overhaul Manual JEM0001-7.

xi. The inspection details are to be noted in the engine maintenance log including any corrective action that was required. Use Form below and include in log. Note the cylinder which was removed and inspected. Quote this service letter in the log (i.e. JSL014-1)

The ‘single cylinder head Inspection’ is a recommended one off procedure for Group 3 (as identified in Table 1 of this Service Letter) Jabiru engines, after which time the normal maintenance schedule resumes.

It is recommended that this ‘single cylinder head inspection’ regime be repeated whenever a cylinder head is removed from the engine. This enables continued monitoring of these components. A note should be made in the engine maintenance log for any additional single cylinder head inspections conducted.

If issues were found or parts needed replacement during the single cylinder inspection it is recommended that this procedure be repeated at the next major service interval (e.g. 100 hourly, annual etc) to ensure that any work conducted on the cylinder head(s) has successfully resolved potential issues that were detected.




2014


2014



of 13

5.2 Follow-On Inspections

Certain of the items noted above may be caused by other defects in the engine, by incorrect operation or by maintenance factors. Operators are encouraged to contact Jabiru Aircraft where issues are found to identify contributing factors and correct them. Note that if the cause is not addressed there is every chance that the issue will recur and an unsafe condition result. In some cases this may ultimately cause engine failure, potentially leading to the loss of the Crew, airframe or engine. A full discussion of these are beyond the scope of this document, however a brief sample is included below.

i. Valve seat recession or “movement”. Most often due to extended operation at elevated temperatures (particularly CHT). Check for leaks in intake/exhaust system and take steps to reduce CHT in operation (i.e. increase climb airspeed, step-climb, minimize ground running etc.)

ii. Valve guide carbon. Potentially due to dirty or excessively hot oil. Poorly sealing valves may also contribute. Check oil change frequency and aircraft operating methods to reduce oil temperature. If leak-down results are poor valves may need to be cleaned or lapped.

iii. Valve stem cracking. Typically due to operation at excess exhaust gas temperatures. Check EGT using EGT sensors such as a fully instrumented EMS (contact Jabiru Aircraft for more information). Check for leaks in intake/exhaust system. Check carburettor settings and mixtures. Check fuel freshness. Check valve is sealing.

iv. Valve collets binding on valve stem. Potentially due to dirty or excessively hot oil. Operations in dusty environments also a potential contributor leading to oil contamination. Check oil change frequency and aircraft operating methods to reduce oil temperature. Check blow-by on piston rings contaminating engine oil.

v. Valve washer wear. Typically related to binding collets. See notes above. Excessively “sharp” spring ends another potential factor.

vi. Valve spring corrosion. Typically caused by storage in humid environments or by not being run often or long enough. Using more frequently or improved inhibition for storage may be required.

vii. Rocker bush wear. May be caused by elevated head, oil or exhaust temperatures. Troubleshoot as noted above.




2014


2014



of 13

6 Jabiru engine manuals

The most current Engine Manuals as referenced by this Service Letter are: i. JEM0001-7 (Jabiru Engine Overhaul Manual)

ii. JEM0002-4 (Jabiru Engine Maintenance Manual)

iii. JEM2202-6 (Jabiru 2200 Engine Installation Manual)

iv. JEM3302-4 (Jabiru 3300 Engine Installation Manual)

7 General Engine Maintenance Notes

The work detailed in this Letter requires extensive skills, experience and training in engine maintenance – as well as special tools and equipment. Unskilled personnel or those lacking the correct tools and training must not attempt this work. Refer to the current Jabiru Engine Overhaul Manual, Document JEM0001 Issue 7 (or later approved issue) for personnel, tool & equipment requirements. The cylinder head could be mailed to Jabiru for checking and reassembly as an option.

8 Reminder of current practices

This section promotes the practices current (at the time of writing) for Jabiru Engine Maintenance as they relate to the components of the cylinder head. Refer to the latest approved revisions of Jabiru Manuals for details.

i. Ensure the engine oil and oil filter are changed at every 25 hourly inspection (as prescribed by the Engine Maintenance Manual – JEM0002). Frequent oil changes reduce the amount of contaminant buildup in the oil which can cause valve seizure. In addition there now exists the requirement for the oil and oil filter to be changed every 6 months if this time elapses before the engine reaches the next 25 hourly.

ii. If an engine is prepared for long term storage, ensure that the current practice (as prescribed in JEM0002) of applying corrosion inhibitor into the each of the rocker chambers is observed.

iii. Ensure the engine carburation system is updated to current jetting configuration as prescribed in the most current Engine Overhaul and Maintenance Manuals (JEM0001 and JEM0002).

iv. Owners and Operators should also familiarise themselves with the Jabiru Service Letter JSL007 (most current issue -4 at the time of this writing) which gives guidance with regards to different fuels and how they affect the engine, particularly the deposits produced in the combustion chamber.

Warning: Several valve failures have been attributed to operating with fuel mixtures containing

both AVGAS and MOGAS. This should be avoided unless absolutely unavoidable.

v. The requirement for 50 hourly cleaning and inspection of the carburettor air filter must be adhered to (and mandatory replacement at every 100 hourly or annual inspections). This minimizes the amount of contaminant inducted into the engine.




2014


2014



of 13

vi. It is recommended that when operating in dusty conditions a more regular air filter

servicing schedule is used. Also remember crankcase breathers are not filtered and, for some earlier aircraft models, neither is intake air with carburettor heat ON.

vii. DO NOT make any unapproved modifications to the valve guide (such as replacement with K-liners) or any other modifications to the componentry of the cylinder heads and the cylinder heads themselves.

viii. DO NOT use top end cylinder lubricants or fuel additives.

8.1 Notes of operation

i. As previously mentioned the oil must now be changed every 6 months if the engine has done less than 25 hours in that time period. This is necessary because engines that are largely inactive will accumulate contaminants including moisture, acids and sludge. These contaminants are expunged from an engine when it is operated regularly. After long periods of inactivity, short ground runs should be avoided as this will not allow enough time for the engine to remove these contaminants which can cause valve sticking.

ii. Exposing the engine to shock cooling during low-powered rapid descents or shutting the engine down hot (i.e. not allowing a sufficient idle period to gradually bring temperatures down) will promote the build-up of contaminants and may induce valves sticking.




2014


2014



of 13

9 Checklist.

Engine Cylinder Head Inspection

Aircraft Registration: Aircraft model:

Engine Serial Number: Date of Inspection:

TTIS for Engine: Inspection done by:

TTIS for Heads:

Response Value TOTAL: Engine Applicability Group:

Task Finding/Corrective Action

Visually inspect the inlet and exhaust valve seat, check the seats do not have excessive carbon buildup and the seats are level in the head (i.e. not protruding or sunken

Inspect the valve guides. Check there is not excessive carbon buildup. Check the diameter of the guide is within the limits specified in the build tolerances table in JEM0001

Inspect both valves, checking for corrosion, cracking, blueing and abrasion on the stem. Inspection the bottom of the stem using a 10X magnifying glass. This area will first need to be polished clean so the surface can be inspected.

Also check the collet grooves on the valves are clean and free from corrosion and other contaminants, clean as necessary. Similarly check the collets themselves. Reassemble the collets on the valve stem and check they can freely rotate without too much friction.

Inspect top and bottom spring washers for wear.

Visually inspect the valve springs with at least 10X magnification. If any nicks, inclusions or corrosion pitting is seen, the springs must be replaced.

Inspect rockers. In particular inspect the condition of the rocker bushes, check the bush for melting or other deterioration. Insert the rocker shaft and check that the rocker moves freely (but not loosely) on the shaft.

Re-assemble and install head

Add a copy of this completed checklist to the engine log book.




2014


2014



of 13

10 Continued Operating Safety Reporting Form

Document: COSM2-1 The owner/operator of a LSA is responsible for notifying the manufacturer of any safety of flight issue or significant service difficulty upon discovery. RETURN DEFECTIVE PART TO JABIRU AIRCRAFT WITH THIS FORM.

Date:

Aircraft Model

Aircraft Registration

Aircraft S/No.

Engine S/No.

Details of item:

Name of Reporter:

Preferred Contact Details of Reporter

Form No.COSR-1

LSA Service Notification: Cylinder Head Inspection


JSN 014-1

Release Date: 1st December,

2014


2014



Page 1 of 1

LSA Service Notification: JSN 014-1

Issue: 1

Effective Date: 13th December, 2014

Subject: Jabiru Cylinder Head Inspection

Applicability:

The content of this directive is applicable to all Jabiru engines:

Requirement:

It is recommended that operators of engines within Light Sport Aircraft categories comply with the requirements of Jabiru Service Letter JSL 014-1

Compliance:

The compliance details are given in JSL 014-1

Background:

This Service Notification has been prepared to make applicable the requirements of JSL 014-1 for engines operating within Light Sport Aircraft Categories.

JSL014-1_Jabiru_Cylinder_Head_Inspection_4.pdf

Documents

Transcript of JSL014-1_Jabiru_Cylinder_Head_Inspection_4.pdf